The Clinical Core serves three main junctions in the Center. 1) Diagnostic characterization of the proband (father), mother, index (child), and siblings; 2) Oversight concerning the procedures for further assessment or referral for subjects manifesting clinically significant problems; and, 3) Supervision of the collection of specimens, including saliva, urine, hair, and blood, and coordination of assays for measures which directly inform the assessment (e.g., urine drug screens, cotinine levels). Central to CEDAR's mission, the Clinical Core is responsible for ensuring accurate and complete adherence to the subject ascertainment criteria, particular with respect to inclusion/exclusion documentation. The Clinical Core, operating through a consensus conference process and using the best estimate diagnostic procedure, determines the diagnoses of all of the subjects participating in the Center's research. Over 3,000 individuals representing 675 families have been evaluated to date. This core also oversees specimen collection, specimen storage, and fidelity to procedures regarding the laboratory analyses Lastly, the Clinical Core oversees compliance with NIDA policies regarding the provision of information on HIV. Analytic tasks, in collaboration with the CISC, pertain to characterizing the sample to both guide and monitor subject recruitment and follow-up.